Sims 3 Store Content Not Showing up in Game

@sevenfourteen87  Please go into Documents > Electronic Arts > The Sims 3 > DCCache and remove all the files that end in .ebc or .tmp.  Go into DCBackup and delete everything there, and move the Downloads folder to the desktop.  This is in case you have custom content you don't want to have to redownload; if you don't, just delete Downloads.

Next, download a fresh copy of one Store item and see whether it installs and shows in-game.  If it does, you can start installing the rest of your Store content, a few items at a time, and make sure to keep testing so you know whether and when the Store items stop working.

If the one new item doesn't install properly, move the entire Sims 3 folder to the desktop, open the launcher to spawn a clean folder, and try again to install one Store item.  Moving the Sims 3 folder will prevent the game from reading your saves or other user content, but that can be addressed later; for now, just see whether the Store content works.